Tape measure device and method of manufacturing blade therefor

ABSTRACT

A tape measure device has an elongated blade with a central concave-convex segment with at least one planar segment adjoining edgewise the central concave-convex segment to form a junction that extends substantially along the entire length of the elongated blade. During formation of the blade the junction is annealed to avoid formation of a flaw or incipient fracture along the junction.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 11/430,340now U.S. Pat. No. 7,174,654, filed May 9, 2006; which is divisional ofapplication Ser. No. 10/945,679, filed Sep. 21, 2004, now U.S. Pat. No.7,096,596, issued Aug. 29, 2006. These related applications areincorporated herein by reference and made a part of this application.Moreover, the inventors incorporate herein by reference any and all U.S.patents, U.S. patent applications, and other documents, hard copy orelectronic, cited or referred to in this application.

DEFINITIONS

The words “comprising,” “having,” “containing,” and “including,” andother forms thereof, are intended to be equivalent in meaning and beopen ended in that an item or items following any one of these words isnot meant to be an exhaustive listing of such item or items, or meant tobe limited to only the listed item or items.

“Rectangular shape” includes square shape.

BACKGROUND OF THE INVENTION

A tape measure is a device used to measure such things as lengthdistance. A tape measure typically comprises an elongated blade that iswound about a reel and stored within a housing. A user employs the tapemeasure by unwinding the elongated blade, extending the blade through anopening in the housing. The elongated blade has rule 1 markings tomeasure length and distance.

Examples of tape measures are disclosed in U.S. Pat. Nos. 1 6,324,769;6,367,161; and 6,662,463. As disclosed in these patents, it is desirablethat an extended portion of the elongated blade be as linear aspossible. For example, the extended blade portion may have a standoutarcuate length of at least ten feet with a horizontal linear lengthgreater than ninety-seven percent of the standout arcuate length. Asthis extended portion increases in length, its tendency to bend downwardalso increases due to the increase in the weight of the extendedportion. This bending tendency is obviated at least to some degree bycontrolling the dimensions of the blade and the materials used in itsconstruction. Additionally, the blade's cross-sectional shape isconfigured to resist bending. For example, the blade's cross-sectionalshape may include a concave-convex central section adjoining one or moreplanar segments. Although this cross-sectional shape resists bending, itpresents a problem; namely, along any junction line where a planarsegment merges with the concave-convex central section, a flaw orincipient fracture is created using conventional stamping a techniquesin manufacturing the elongated blade.

SUMMARY OF THE INVENTION

This invention has one or more features as discussed subsequentlyherein. After reading the following section entitled “DETAILEDDESCRIPTION OF ONE EMBODIMENT OF THIS INVENTION,” one will understandhow the features of this invention provide its benefits. The benefits ofthis invention include, but are not limited to, providing a tape measureblade having a cross-sectional configuration that resists bending butavoids during manufacture the formation of flaws or incipient fractures.

Without limiting the scope of this invention as expressed by the claimsthat follow, some, but not necessarily all, of its features are:

One, the tape measure device of this invention includes an elongatedblade that, when in an extended position, has a predeterminedcross-sectional curvature formed by a concave-convex segment and atleast one planar segment adjoining edgewise the concave-convex segment.At the adjoining edges of these segments a junction is formed thatextends substantially along the entire length of the elongated blade.This junction is annealed during formation of the blade to avoidcreating a flaw or incipient fracture along the junction.

Two, annealing may comprise passing a substantially flat strip ofmetallic material lengthwise through a slit opening in a die and heatingthe strip. The flat strip of metallic material is heated to atemperature substantially above ambient temperature but below themelting point of the metallic material. The die or the material may beheated, or both may be heated, or the flat strip of metallic materialmay be heated prior to passing it through the slit opening. The metallicmaterial may be selected from the group consisting of chromium, nickel,carbon, and iron. A strip made from these materials is flexible andresilient material. In the case of steel strip material, the strippasses through the die at a rate from about 100 to about 200 linear feetper minute and is heated to a temperature from about 500 to about 700degrees Fahrenheit.

Three, the slit opening has a configuration substantially conforming tothe predetermined cross-sectional curvature of the blade. In oneembodiment, the predetermined cross-sectional curvature of the extendedblade portion has predetermined dimensions and the slit opening hasdimensions that are slightly less than the predetermined dimensions ofthe cross-sectional curvature of the extended blade portion. Uponpassing such a smaller dimensioned metallic strip through the slit inthe die, the ductile metallic material is worked, i.e., stretched.

Four, the flat strip of metallic material may have a minimum ofthickness of at least about 0.0030 inch, for example, from about 0.0045to about 0.0060 inch, and a width from about 0.500 to about 1.625inches. In one embodiment, the predetermined cross-sectional curvaturecomprises a central concave-convex segment straddled by a pair of planarsegments. The central concave-convex segment may have a radius ofcurvature from about 0.5 to about 1.0 inch, and the planar segments eachmay have a width from about 0.25 to about 0.75 inch. The planar segmentsmay be substantially equal in width.

These features are not listed in any rank order nor is this listintended to be exhaustive.

BRIEF DESCRIPTION OF THE DRAWINGS

One embodiment of this invention, illustrating all its features, willnow be discussed in detail. This embodiment depicts the novel andnon-obvious tape measure device of this invention as shown in theaccompanying drawing, which is for illustrative purposes only. Thisdrawing includes the following Figures (Figs.), with like numeralsindicating like parts:

FIG. 1 is a perspective view of the tape measure device according to oneembodiment of this invention.

FIG. 2 is a side view of the tape measure device shown in FIG. 1 withportions broken away and the blade completely retracted.

FIG. 2A is a side view similar to that of FIG. 2 with portions brokenaway and the blade partially unwound and a portion thereof in anextended position.

FIG. 3 is a cross-sectional view of the elongated blade taken along line3-3 in FIG. 2A.

FIG. 3A is a partial, cross-sectional view of the elongated blade takenalong line 3A-3A in FIG. 3.

FIG. 3B is a partial, cross-sectional view of the elongated blade takenalong line 3B-3B n FIG. 3.

FIG. 3C is a plan view taken along line 3C-3C in FIG. 3.

FIG. 3D is a plan view taken along line 3D-3D in FIG. 3.

FIG. 4 is a perspective view illustrating a flat strip of metal passingthrough a die to form the blade according to this invention.

FIG. 5 is a plan view of the blade illustrating the ruled markings onthe surface of the blade used in the tape measure device shown in FIG.1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown in FIGS. 1 through 3, the tape measure device 10 of the presentinvention includes an elongated blade 20 heat-treated and worked inaccordance with this invention. This blade 20 is stored in a wound-upcondition in a blade holding assembly 14 mounted to a housing 12. Asshown in FIG. 5, the elongated blade 20 has on at least one surfacegraduated markings 50, for example ruled lines denoting inches andfractions thereof, located on a top side 20 d, thus allowing a user tomeasure length or distance. Ruled lines denoting metric lengths ordistance may also be used. The housing 12 is a box-like structure havinga substantially rectangular shape when view from the side as shown inFIG. 2. Within the housing 12 is an internal chamber 12 c that receivesa reel 18, a component of the blade holding assembly 14. The blade 20has an internal end 20 c connected to the reel 18 and a free end 20 bextending outwardly through an opening 12 a in the housing 12.

As shown in FIG. 2A, the blade holding assembly 14 is of conventionaldesign, being manually actuated to hold a selected portion 60 (FIG. 2A)of the blade 20 in an extended position and manually actuated to releasethe extended blade 20, rewinding the blade portion 60 about the reel 18.The blade 20 is unwound manually to extend outwardly from the opening 12a in the housing 12 any selected portion 60 of the blade 20 asdetermined by the user. The blade holding assembly 14 includes the reel18 about which the blade 20 is normally completely wound about as shownin FIG. 2 and a button 14 a on the exterior of the housing 12 foroperating a brake 12 b located within the housing 12. In one position ofthe button 14 a as shown in FIG. 2, the brake 12 b is disengaged. Inanother position shown in FIG. 2A, the brake 12 b is engaged to hold theselected extended portion 60 in place. The blade 20 may be withdrawnfrom the housing 12 when the brake 12 b is engaged, so the blade is heldin any desired extended position. Release of the brake 12 b initiatesthe rewinding of the extended blade portion 60.

The reel 18 is mounted within the internal chamber 12 c for rotation. Itincludes a cylinder 18 c, a coil spring 18 a operatively disposed withinthe cylinder 18 c, and a central shaft 18 b connected to the housing 12about which the reel rotates. The coil spring 18 a has one end 18 dattached to the central rod 18 b and its other end 18 e attached to thecylinder 18 c. The coiled spring 18 a is tightened as the blade 20 ismanually pulled from the housing 12 so that it may rewind the extendedportion 60 of the blade 20 onto the reel 18 upon manipulation of thebutton 14 a to release the brake 12 b. The blade 20 is attached at itsone end 20 c to the cylinder 18 c. As the blade 20 is pulled from thehousing 12, it extends tangentially to the cylinder 18 c.

The brake 12 b is located within the housing 12 and with the button 14 ain the position shown in FIG. 2A, the brake is engaged to push against awound-up portion 20 a of the elongated blade 20 to inhibit the reel 18from rotating but not so strong as to prevent a user from furtherunwinding the blade from the reel 18. As the blade 20 is extended, thebrake 12 b as shown in FIG. 2A continuously presses against the wound-upportion 20 a, holding the blade in any desired extended position (FIG.2A) until the user pushes the button 14 a, sliding the button upward asviewed in FIG. 2A along the exterior of the housing 12, moving thebutton to its disengaged position shown in FIG. 2. Pushing the button 14a upward, lifts the brake 12 b from the wound up portion 20 a. Due tothe action of the spring 18 a, the reel rotates counter-clockwise asviewed in FIG. 2A, rewinding the blade 20 around the reel 18 to flattenthe blade as it is wound about the reel. The blade holding assembly 14thus enables the user to control the operation of the reel 18 so theblade remains in the selected extended position until the button 14 a isactuated.

The extended portion 60 of the blade 20 has a curved cross-section asshown in FIG. 3. The blade 20 is substantially flat when wound about thereel 18 and its topside 20 d faces the reel and its bottom side 20 efaces away from the reel. The blade 20 in the wound up and flattenedcondition may have a width of at least about 1 inch, for example, fromabout 1.600 to about 1.625 inches. The blade's thickness may be about0.0045 inches, for example, from about 0.0030 to about 0.0060 inches.The extended portion 60 of the blade 20 has a cross-sectional curvatureC that is substantially uniform along the entire length 1 of theextended portion 60. This cross-sectional curvature C comprises anarcuate, concave-convex central section 40 and a pair of lateral,substantially flat planar end segments 42, 44 that straddle theconcave-convex central section. The adjoining edges of the planar endsegments 42, 44 and central section 40 merge at the junction line J1 andJ2 extending along the length of the blade 20. The arcuate,concave-convex central section 40 may have a radius of curvature r₁ fromabout 0.5 inch to about 1.0 inch, a height h₂ from about 0.100 inch toabout 0.250 inch, a width w₁ from about 0.600 2 inch to about 0.925inch, and spans an angle a₁ from about 71.0 degrees to about 105.0degrees. The extended, elongated blade 60 has a blade height h₁ fromabout 0.125 inch to about 0.500 inch, and a width w₂ from about 0.925inch to about 1.25 inch. Each of the planar end segments 42, 44 has awidth w₃ and w₄, respectively, that are equal, for example from about0.250 inch to about 0.750 inch.

The extended portion 60 of the elongated blade 20 may have a standoutarcuate length of at least ten feet with a horizontal linear lengthgreater than ninety-seven percent of the standout arcuate length. Whenwound-up around the reel 18, the blade 20 is flattened. Upon moving fromthe selected extended position (FIG. 2A) to the wound-up position (FIG.2), the lateral planar segment 42 moves in a counter-clockwise directionas viewed in FIG. 3, and the lateral planar segment 44 moves in aclockwise direction as viewed in FIG. 3.

In accordance with one feature of this invention, an annealing processis employed to form the blade 20. Referring to FIG. 4, the elongatedblade 20 is formed from a flat strip of metallic material 30 that isheat-treated and worked according to this invention. The flat stripmetallic material 30 may be selected from the group consisting ofchromium, nickel carbon, and iron. The flat strip of metallic material30 is heated and passed through a die 36 with a slit 34 having a shapeand dimensions that are substantially identical to those of thecross-sectional curvature C of the blade 20. Specifically, the slit 34has a concave-convex pattern 70 straddled by a pair of lateral planarend segments 72, 74 to produce a curved metal strip 32. The temperatureis sufficient to heat the flat strip of metallic material 30 aboveambient temperature but below its melting point, for example, a steelstrip is heated to a temperature from about 500 to about 700 degreesFahrenheit. The die may also be heated. Such a flat strip of the steelmaterial 30 may pass through the slit 34 in the die 36 at a rate fromabout 100 to about 200 linear feet per minute. The slit 34 may havedimensions that are slightly less that the cross-sectional dimensions ofthe cross-sectional curvature C of the blade 20 to work the strip ofmetallic material 30, pulling the ductile metallic material slightly asit passing through the slit 34. The curved steel strip 32 as it emergesfrom the die 36 is cooled to ambient temperature to complete theannealing process.

SCOPE OF THE INVENTION

The above presents a description of the best mode contemplated ofcarrying out the present invention, and of the manner and process ofmaking and using it, in such full, clear, concise, and exact terms as toenable any person skilled in the art to which it pertains to make anduse this invention. This invention is, however, susceptible tomodifications and alternate constructions from that discussed abovewhich are fully equivalent. Consequently, it is not the intention tolimit this invention to the particular embodiment disclosed. On thecontrary, the intention is to cover all modifications and alternateconstructions coming within the spirit and scope of the invention asgenerally expressed by the following claims, which particularly pointout and distinctly claim the subject matter of the invention:

1. A method of manufacturing an elongated blade for a tape measuredevice from a substantially flat strip of metallic material, saidelongated blade having a predetermined cross-sectional curvedconfiguration comprising a concave-convex segment and at least oneplanar segment adjoining edgewise the concave-convex segment to form ajunction that extends substantially along the entire length of theelongated blade, said method comprising: passing a substantially flatmetallic strip through a slit opening in a die, said slit opening havinga configuration substantially conforming to said predeterminedcross-sectional curved configuration; annealing said junction to avoidformation of a flaw or incipient fracture along the junction; where theannealing comprises passing said flat metallic strip lengthwise throughthe slit opening and heating to a temperature substantially aboveambient temperature but below melting point of the metallic material,and where the flat strip of metallic material is heated prior to passingsaid strip through the slit opening, and, further, where the die isheated to a temperature substantially from 500 to 700 degreesFahrenheit; and where the metallic material is selected from the groupcomprising chromium, nickel, carbon, and iron.
 2. The method of claim 1where the predetermined cross-sectional curvature of the extended bladeportion has predetermined dimensions and the slit opening has dimensionsthat are slightly less than said predetermined dimensions of thecross-sectional curvature of the extended blade portion.
 3. The methodof claim 1 where the strip passes through the die at a ratesubstantially from 100 to 200 linear feet per minute.
 4. A method ofmanufacturing an elongated blade for a tape measure device from asubstantially flat strip of metallic material, said elongated bladehaving a predetermined cross-sectional curved configuration comprising aconcave-convex segment and at least one planar segment adjoiningedgewise the concave-convex segment to form a junction that extendssubstantially along the entire length of the elongated blade, saidmethod comprising: passing a substantially flat metallic strip through aslit opening in a die, said slit opening having a configurationsubstantially conforming to said predetermined cross-sectional curvedconfiguration; annealing said junction to avoid formation of a flaw orincipient fracture along the junction; where the annealing comprisespassing said flat metallic strip lengthwise through the slit opening andheating to a temperature substantially above ambient temperature butbelow melting point of the metallic material, and where the flat stripof metallic material is heated and the die is simultaneously heated asthe flat strip of metallic passes through the slit opening; and wherethe die is heated to a temperature substantially from 500 to 700 degreesFahrenheit.
 5. The method of claim 4 where the predeterminedcross-sectional curvature of the extended blade portion haspredetermined dimensions and the slit opening has dimensions that areslightly less than said predetermined dimensions of the cross-sectionalcurvature of the extended blade portion.
 6. The method of claim 4 wherethe strip is steel and passes through the die at a rate substantiallyfrom 100 to 200 linear feet per minute.
 7. The method of claim 4 wherethe metallic material is selected from the group comprising chromium,nickel, carbon, and iron.